For the past month the inside of my house has been plagued with a low frequency hum/vibration. If you imagine living next to a mains power station, its that kind of power hum. It can be heard in the garden and areas surrounding the house. I can say that I experience it louder in a specific area outside...however there is nothing there, no power lines or pipes etc. I have tried cutting the power and water to the building and it still occurs which makes me think that it is coming from one of my neighbours. Only think is that at enough distance from the house it gets hard to distinguish due to external noise. I am looking to try and find a way to record and locate the source of the sound. Doe anyone have any experience in attempting to record low frequency noise or know where such equipment could be obtained?